The present invention relates to a superconducting transmission delay line phase shifter.
Phase shifters are one of the most important elements for phased array antenna. In the prior art, ferrite phase shifters have been used due to their high operation speed and a low energy loss. On the other hand, ferrite phase shifters have disadvantages by virtue of their large scale and large weights as well as complicated structures.
There has been known a PIN diode phase shifter having small weight, small scale, and low cost. On the other hand, PIN diode phase shifter shows a large insertion loss, for which reason it is necessary to provide an amplifier of the bottom stage of the delay circuit including the superconducting transmission delay line phase shifter.
There has been known a ceramic diode phase shift having small weight, small scale, and low cost. On the other hand, a ceramic diode phase shifter shows a large insert loss, for example, 5 dB.
Superconducting quantum interface devices (SQUIDs) have been known and disclosed in 1992 IEEE MIT-S Digest. Such a device suffers from the fact that a phase shift appears at a lower temperature than Tc.
A dielectric resonator having a copper cavity is disclosed in Applied Physics Letters Vol. 63, No. 23, 1993, wherein there is reported the effect of a dielectric field on the effective microwave surface impedance of YBa.sub.2 Cu.sub.3 O.sub.7 /SrTiO.sub.3 /YBa.sub.2 Cu.sub.3 O.sub.7 trilayers. The resonant frequency controllable by controlling the electric field is only about 10 kHz. If the frequency to be used is 24 GHz, the resonator can show a slight phase shift of 1.5.times.10.sup.-4 degrees, which is insufficient for realizing the actual phase shifter.